Whether it is closed source or open source is a make-it or break-it for many developers, so I hope it will be open source. Whether it is free or not is another matter: I’d like it a lot to be free, particularly since I would have a lot of difficulty paying for it, but having it open source is even more important. I’d be particularly annoyed at DRM-like protections, and even partly annoyed at licenses, but I’m sure we can expect better from Atom’s developers.

Atom won’t be closed source, but it won’t be open source either. It will be somewhere inbetween, making it easy for us to charge for Atom while still making the source available under a restrictive license so you can see how everything works. We haven’t finalized exactly how this will work yet. We will have full details ready for the official launch.

What kind of restrictive license? Just being able to see how everything works isn’t good enough; what if someone wants to hack on the core and eventually become a part of the team? Do they have to be hired first by Github before they can touch the core?

I would highly recommend the GPL in a situation like this or at least a GPL-compatible license.

As I understand it, you will be able to look at the source, fork it, improve it and make pull requests, but you won’t be allowed to redistribute your modified version of Atom, so unless your changes get accepted by Github, you can’t share them with other users.

It does make sense. It means you can pretty much do everything you can do with an open source app, but you can’t take it and create your own app based upon it, like xemacs did with emacs or IcedCoffeeScript with CoffeeScript. This isn’t a technical limitation, but a legal one. Of course you could just take the source and do whatever you want with it, but it would not be legal, you’d commit copyright infringement because the license won’t allow you to redistribute it since Github wants to sell this. Otherwise someone could just fork it and offer it for free.

I disagree. That is rarely done, so it can’t be the whole point of open source. Usually the point of open source is to be able to fix bugs and add new features and you can still do that with this. You can’t do hostile forks. That’s the limitation.